GI microbiology Flashcards
How is rotavirus spread?
Faecal-oral route
What is the clinical presentation of rotavirus infection?
Fever, then vomiting, then diarrhoea
Does rotavirus cause bloody diarrhoea?
No
Does rotavirus have a high or a low infectious dose?
Low - 100-1000 particles required for infection
Which part of the GI tract does rotavirus have an effect on?
Affects absorption and secretion in the bowel
How is rotavirus diagnoses?
PCR on faeces
What might affect children after infection with rotavirus?
Post-viral malabsorption, causing more diarrhoea
How is the rotavirus vaccine administered?
Orally
What form does the rotavirus vaccine take?
Live attenuated
Where is the rotavirus vaccine excreted?
Faeces
How is norovirus spread?
Faecal-oral route
Droplets
Does norovirus have high or low infectious dose?
Low
What is the clinical presentation of norovirus?
Explosive, sudden onset diarrhoea and vomiting
How long does norovirus infection tend to last?
2-4 days
How is norovirus diagnosed?
PCR on faeces
How is infection with norovirus managed?
Hydration
Cohort nursing/isolation in hospitals
What toxins might C difficile produce?
Enterotoxin
Cytotoxin
Spores
What is the usual cause of C difficile infection?
Disruption of normal gut flora
Antibiotic use
What complication might be cause by C difficile infection?
Pseudomembranous colitis
How common are relapses in C difficile infection?
Occur in 30% of cases
What are some of the risk factors for development of C diff?
Antibiotic use
Recent surgery
Hospital admission
Use of PPI
What two tests must be positive for diagnosis of C diff to be made?
C diff antigen
C diff toxin
What is food poisoning?
Illness caused by eating food contaminated with micro-organisms, toxins, poisons etc.
What is the most common bacterial cause of food poisoning?
Campylobacter
Which bacteria have a short incubation period and how long is this incubation period usually?
Bacillus cereus
Staph. aureus
1-6 hours
What symptoms would patients usually present with in food poisoning with a bacteria of short incubation period?
Vomiting
Abdominal pain
How long is the usual incubation period for campylobacter?
16-48 hours
What kinds of food may be contaminated with campylobacter?
Poultry
Milk
What are some of the symptoms and signs of campylobacter infection?
Pain
Fever
Diarrhoea
Bloody in 30% of cases
How long is the usual incubation period for salmonella enteritidis?
12-48 hours
What are some of the symptoms of salmonella enteritidis?
Diarrhoea
Vomiting
Blood
Fever
What foods might salmonella be present in?
Poultry
Meat
Eggs
Why is serogrouping of salmonella useful?
It can help pinpoint the source of infection, and so is useful for detecting outbreaks
What are the most common serotypes of salmonella?
B, C & D
What does E. Coli O157 present with?
Bloody diarrhoea
Does E. Coli O157 have a low or a high infectious dose?
Low
What kinds of food might E. Coli O157 have contaminated?
Beef
Raw milk
What toxin does E. Coli O157 produce?
Verotoxin
What is a potential complication of verotoxin production from E. Coli O157?
Haemolytic uraemic syndrome (HUS)
Patients within which age group tend to develop HUS?
< 16
What is the clinical presentation of HUS?
Abdomina; pain Fever Pallor Petechiae Oliguria Bloody diarrhoea in 90% of cases
What blood abnormalities might HUS show?
High white cells Low platelets Low haemoglobin Red cell fragments LDH > 1.5 x normal
What does verotoxin do?
Binds to receptors found on renal cells, RBC & others -
Inhibit protein synthesis
Causes cell swelling, intravascular coagulation and platelet aggregation
Causes mechanical damage to RBC
What tests should be done in suspected diagnosis of HUS?
Send U&E, FBC, film, LFT, clotting, urine, (dipstick/micro), lactate dehydrogenase
Stool culture should be done on all bloody diarrheoa
What are some of the complications of HUS?
Acute renal failure
Thrombocytopaenia
Haemolytic anaemia
What is the most common cause of bloody diarrhoea in children?
E. Coli O157
